The present invention relates generally to semiconductor manufacturing technology and more specifically to electroplating systems with consumable electrodes.
In the past in the manufacture of semiconductors, there have been numerous processes which required plating at various stages to deposit various materials on semiconductor wafers. All of these systems generally required human operator monitoring or the addition of plating materials at timed intervals. Since the addition of plating material was deemed to be one which required a certain degree of expertise and experience, it was not thought to be possible to automate this type of operation without complex, and expensive, computer equipment.
As the industry has sought to make smaller and smaller semiconductor devices with finer and finer device connections, it has been found that conventional metallization techniques for making the device connections are inadequate for future generations of products. This has resulted in the shift from materials such as aluminum (Al) to copper (Cu).
Copper is not suited for deposition using the metallization techniques used for aluminum and is better adapted for deposition by electro- or electro-less plating processes out of a solution. With the adoption of the copper interconnect, the device connection technology, there has been a great deal of effort placed into automating copper plating technology for semiconductors. This has meant the introduction of expensive equipment. This in turn has meant that much effort has been expended in trying to reduce costs.
One approach involved a recirculating system for the plating chamber to which more metal ion was added as it was deposited on the semiconductor wafer. The problem with this approach is that there is a need to add metal ion in a chemical compound such as copper sulfate (CuSO4) for Cu, which tends to disturb the stability of the chamber.
A solution for solving this problem simply and inexpensively has been long sought by and eluded those skilled in the art.
The present invention provides an electroplating system for seed layer covered semiconductor wafers in which a plating chamber is provided with an inert primary anode conneetible to a positive voltage source and a semiconductor wafer connector connectible to a negative voltage source. The plating chamber further contains a consumable ring secondary anode connectible to the positive voltage source such that, when the plating chamber is filled with a plating solution and a semiconductor wafer is connected to the semiconductor wafer connector, and the voltages are connected, the semiconductor wafer will be plated by consuming the consumable ring secondary anode. This eliminates the need to add chemicals which disturb the stability of the plating solution and which cause spiking of the metal ions.
The present invention further provides a copper (Cu) electroplating system for copper seed layer covered semiconductor wafers in which a plating chamber is provided with an inert platinum (Pt) anode connectible to a positive voltage source, and a semiconductor wafer connector connectible to connect the copper seed layer to a negative voltage source. The plating chamber further contains a consumable ring secondary anode connectible to the positive voltage source such that, when the plating chamber is filled with a plating solution and a semiconductor wafer is connected to the semiconductor wafer connector, and the voltages are connected, the semiconductor wafer will be plated by consuming the consumable ring secondary anode. This eliminates the need to add copper sulfate (CuSO4) solutions which disturb the stability of the plating solution and which cause spiking of the copper ions).
The above and additional advantages of the present invention will become apparent to hose skilled in the art from a reading of the following detailed description when taken in conjunction with the accompanying drawings.